In March 2023, the Japanese medical authorities announced that the new weight loss drug Wegovy—which was in staggering demand across the world, causing shortages everywhere—had been approved to treat obesity in their country. It sounded, at first glance, like great news for Novo Nordisk, the company that makes Ozempic and Wegovy. But industry outlet the Pharma Letter explained that this would not in fact turn out to be much of a boost. They predicted that these drugs would dominate the market in Japan, but that won’t mean much, for a simple reason: there is almost no obesity there. Some 42% of Americans are obese, compared with just 4.5% of Japanese people. Japan, it seems, is the land that doesn’t need Ozempic.

I wondered how this could be, and if the answer might offer me a way out of a dilemma that was obsessing me. Several months before, I had started taking Ozempic, and I was traveling all over the world to interview the leading experts on these drugs to research my new book, Magic Pill: The Extraordinary Benefits and Disturbing Risks of the New Weight-Loss Drugs. The more I discovered, the more torn I became. I had learned there are massive health benefits to reversing obesity with these drugs: for example, Novo Nordisk ran a trial that found weekly injections reduced the risk of heart attack or stroke by 20% for participants with a BMI over 27 and a history of cardiac events. But I also saw there are significant risks. I interviewed prestigious French scientists who worry the drugs could cause an increase in thyroid cancer, and eating disorders experts who worry it will cause a rise in this problem. Other experts fear it may cause depression or suicidal thoughts. These claims are all fiercely disputed and debated. I felt trapped between two risky choices—ongoing obesity, or drugs with lots of unknowns.  ...

I glimpsed part of the explanation when I went to the Tokyo College of Sushi & Washoku, to interview the president Masaru Watanabe, who I also spoke with on Zoom on another occasion. He had agreed to cook a meal for me with some of his trainees, and to explain the principles behind it. He told me: “The Japanese cuisine’s [core] feature is simplicity. For us, the simpler, the better.”  ...

In Japan, you are taught from a very early age to only eat until you feel you are 80% full. It takes time for your body to sense you’ve had enough, and if you hit a sense of fullness while you are still eating, then you’ve definitely had too much.   ...

Up until this point, I had seen aspects of Japan’s approach toward health that seemed totally admirable. But next, I saw something that left me with mixed feelings. In 2008, the Japanese government noticed that obesity was slightly rising. So they introduced the “Metabo Law,” which was designed to reduce the negative consequences of a large waistline. The law contained a simple rule. Once a year, every workplace and local government in Japan has to bring in a team of nurses and doctors to measure the waistline of adults between ages 40 and 74. If the measurements are above a certain level, the person is referred to counseling, and workplaces draw up health plans with employees to lose weight. Companies with fattening work forces can face fines. ...